firmware: arm_scmi: fix divide by zero when sustained_perf_level is zero

sudeep-holla · olofj · commit 96d529bac562 · 2018-09-06T09:59:40.000-07:00
Firmware can provide zero as values for sustained performance level and corresponding sustained frequency in kHz in order to hide the actual frequencies and provide only abstract values. It may endup with divide by zero scenario resulting in kernel panic. Let's set the multiplication factor to one if either one or both of them (sustained_perf_level and sustained_freq) are set to zero. Fixes: a9e3fbf ("firmware: arm_scmi: add initial support for performance protocol") Reported-by: Ionela Voinescu <ionela.voinescu@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Olof Johansson <olof@lixom.net>
diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
@@ -166,7 +166,13 @@ scmi_perf_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
 					le32_to_cpu(attr->sustained_freq_khz);
 		dom_info->sustained_perf_level =
 					le32_to_cpu(attr->sustained_perf_level);
-		dom_info->mult_factor =	(dom_info->sustained_freq_khz * 1000) /
+		if (!dom_info->sustained_freq_khz ||
+		    !dom_info->sustained_perf_level)
+			/* CPUFreq converts to kHz, hence default 1000 */
+			dom_info->mult_factor =	1000;
+		else
+			dom_info->mult_factor =
+					(dom_info->sustained_freq_khz * 1000) /
 					dom_info->sustained_perf_level;
 		memcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE);
 	}
